Hydraulic press.



G. E. STEVENS.

HYDRAULIC PRESS.-

APPLICATION FILED DEC- S, 1915 1,240,61 7. Patented Sept. 18, 1917.

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Inventor,

Geor-e 5., Stevens,

G. E. STEVENS.

HYDRAULIC PRESS.

APPLICATION FILED 050.5. 1915.

Patented Sept. 18

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iii/E. Stevens,

G E. STEVENS.

HYDRAULIC PRESS.

APPLICATION FILED DEC. 6. 1915.

1,240,617. PatentedSept.18,191?.

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as 60 I Inventor:

George BStevens witty.

G. E. STEVENS.

HYDRAULIC PRESS.

APPLICATION FILED 05c. s. 1915.

1,240,617. PatentedSpt.-18, 191?.

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. Inventor;- George E. Stevens,

UNITED STATES PATENT OFFICE.

GEORGE E. STEVENS, OF LYNN, MASSACHUSETTS, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

HYDRAULIC PRESS.

Specification of Letters Patent.

Patented Sept. 18, 1917.

To all whom it may concern:

Be it known that I, Gnonon E. STEVENS, a citizen of the United States, residing at Lynn, county of Essex, State of Massachusetts, have invented certain new and useful Improvements in Hydraulic Presses, of which the following is a specification.

The present invention relates to hydraulic presses and more especially to those used in foundries for core making.

The object of. my invention is to improve the construction of hydraulic presses generally, and specifically of the type above mentioned. One of my improvements is di rected to the idea of quickly moving the ram from its position of rest through a portion of its travel, and then to complete the movement more slowly, but under a considerably greater force until the pressure exerted on the work located between the-table carried by the ram and a suitable abutment reaches the desired amount.

Another of my improvements is directed to the idea of quickly lowering the ram and table after the work has been subjected to the desired pressure.

Still another improvement is to combine the pump for supplying the fluid pressure, the driving motor therefor, and the press, all in one structure whereby the same may be readily transferred from place to place without the necessity of uncoupling and coupling heavy piping, etc.

For a consideration of what I believe to be novel and my invention, attention is directed to the accompanying description and the claims appended thereto.

In the accompanying drawings which illustrate one of the embodiments of my invention, Figure l is a view in front elevation of my improved hydraulic press; Fig. 2 is a vertical section thereof; Fig. 3 is a vertical section through the cylinder and ram; Fig. 4 is a section taken on line H of Fig. 2 and looking down; Fig. 5 is a vertical section through the controlling valve; Fig. 6 is a partial section taken on line 6-6 of Fig. 5; Fig. 7 is a detail view chiefly in horizontal section showing the valves for controlling the action of the ram and the by-pass for the quick release of fluid from the cylinder, and Figs. 8, 9 and 10 are detail views of the cylinder and valve seat therein.

8 indicates the base of the press from which rises the cylinder 9. 10 indicates the ram and 11 a work-carryingtable that is supported thereby. 12 indicates in dotted lines the work (in this case a flask contain ing core material) which is to be subjected to pressure by the ram. Situated above the table and in line therewith is an abutment 13 which is carried by a beam 14. The beam is supported at its ends by vertical rods 15 which are provided with heads 16 at their lower ends through which the pivots 17, Fig. 2, extend. In order to hold the abutment over the work-carrying table and in line therewith a horizontal arm 18, Figs. 1 and 4, is mounted on the left-hand head 16 and is normally held in the position shown by the compression spring 19, the latter being seated on the bracket 20. To the outer end of the arm 18 is attached a rod 18 which passes up through the bracket 20 and has an adjustable stop nut on its upper end. The spring 19 surrounds this rod and said not limits the downward movement of the outer end of the arm under spring pressure, said spring yielding when the arm is raised by pushing the beam backward and away from the operator. The reason for mounting the abutment 13 on a swinging support is to insure substantially uniform pressure on the work and to permit the top part of the flask to be removed.

To make the press self-contained a double plunger pump 21 is provided and mounted on a bracket formed integral with the base 8. In the base of the pump is a fluid supply chamber 22 as best shown in Fig. 7, the walls of said chamber forming a support for the driving motor. The pump comprises two plungers 25, each connected to a crank 26, which in turn are driven by gears 27. These gears mesh with a pinion 28 mounted on the armature shaft of an electric motor 29. The motor normally operates at or about constant speed and the pressure delivered by the pump will be substantially uniform. The pump plungers operate in alternation and their cylinders receive fluid from the supply chamber 22, said fluid passing the suction valves 30, of which one is shown. Fluid under pressure is delivered to the cylinder of the press by the pipe 31 and is returned to the supply chamber or receiver 22 by the pipe 32 and also by a by-pass to be described later.

Referring more particularly to Figs. 2 and 3, the cylinder 9 is provided with a .bined check and exhaust valve 39.

central tubular member 33 which is held in place by a nut at its lower end. This member contains a vertical passage 34 through which fluid under pressure is delivered for raising the ram. Fluid is admitted to the tubular member by a passage 35 that in efi'ect forms a continuation of the supply pipe 31. Surrounding the tubular member and engaging a shoulder thereon is a valve seat 36 containing segmental ports 37 and 38, Figs. 7 and 9, through which fluid enters and is discharged from the cylinder. In the bottom of the cylinder is turned a horseshoe shaped groove 38, Figs. 7 and 8, which in turn communicates by a lateral opening with the by-pass 38 to be described later. The ends of the groove 38 are placed in communication by the cross-over passage that is formed by recesses 38 in the valve seat as best shown in Figs. 9 and 10. Mounted above the valve seat 36 is a c3311]- 1e valve is made in the form of a flat disk having an elongated central opening to permit it to be moved to and fro with respect to the tubular member 33. The valve is pivotally attached to a reciprocating actuator 40 by a pin 41. The purpose of this valve is three-foldfirst, to admit fluid to the cylinder when the ram is being elevated by the fluid that passes through the tubular member and a suction is created in the portion of the cylinder surrounding said member; second, to close when fluid under pressure is admitted to the entire cylinder from the passage 34, and third, to uncover the ports in the valve seat 36 and permit the contents of the cylinder to be discharged, as will appear more fully hereinafter. The ram 10 is provided with a cylindrically walled recess 42 which makes a sliding or telescopic fit with the tubular member 33. When the parts are in the position shown in Fig. 2, it will be seen that the working face of the ram is divided into two parts, of which the surface area of one is represented by the surface 43 and that of the other by the surface 44. This arrangement forms in efl'ect a compound or double area ram of which one part is larger than the other, said parts acting in succession, the smaller one first. It is further to be noted that the ram itself controls the flow of fluid under pressure from the passage 34 to the outer part of the cylinder thereby obviating the use of a valve at this point. To start the ram into operation fluid is admitted through the tubular member and the ram rises rapidly, because the amount of fluid delivered by the pumps is substantially constant and because the cubical space in the recess of the ram is comparatively small. As the ram rises it is evident that the outer or larger portion, as represented by the surface 44:, will create a suction and that some means must be provided for filling this cylinder space, since otherwise the ram would be obliged to stop in its upward movement after the passage in the tubular member was exposed by the movement of the ram until the main or outer portion of the cylinder could be filled with fluid from the passage 34. Obviously such a condition would be highly undesirable. I avoid this objection by providing the check valve 39 which opens inwardly due to the suction effect of the outer part of the ram as it rises. I have shown this valve in the raised position in Fig. 3 for the purpose of illustration, but when the ram is in the position shown and high pressure fluid is being admitted to the entire cylinder, the check valve will be on its seat.

It is evident by cutting off the supply of high pressure fluid to the tubular member and exposing the passage therein to the reservoir or supply chamber, that the ram will descend under its own weight until its lower end closes the communication between the passage 34 and the outer part of the cylinder. The fluid contained in the recess will continue to exhaust through the member, but the ram cannot descend unless some means are provided for draining the portion of the cylinder around the member. To this end I mount the valve 39 on the actuator 40 as previously described, and by pulling it sidewise cause it to expose the ports 37 and 38 which in turn open into the groove 38 that is in communication with the by-pass 38 Under the condition just specified the valve acts as an exhaust valve. By this arrangement it will be seen that the ram will rise quite rapidly for a predetermined portion of its stroke, and thereafter, when the lower end of the ram exposes the passage 34, at a slower rate because the cubical space to be filled with fluid has been materially enlarged, whereas the pump continues to deliver substantially the same amount of fluid. It is evident there will be no stopping of the upward movement of the ram when it exposes the end of the passage 34 because the cylindrical space around the member has been gradually filled with fluid that flows past the check valve 39.

I have illustrated arrangement whereby the working surface of the ram is divided into two parts, but my invention is not limited to said arrangement unless so specifled in the claims. The advantage of having the tubular member project into a recess or cylinder in the ram instead of having a projection or extension on the ram entering a smaller cylinder resides in the fact that the total height of the cylinder structure can be materially reduced. As a matter of actual practice, it is reduced by substantially the length of the portion of the tubular member that rises above the valve 39. It

also results in a decrease in weight which means a saving in first cost and a reduction in the height of the apparatus as a whole. As shown, the ram when in the position shown in Fig. 3 rises above the end of the tubular member. This is not essential. The same effect can be obtained by having a port in the side of the member which is exposed by the end'of the ram at some predetermined point in its stroke. In other words, the effective length of the member is that at which the ram permits communication between passage 34 and the portion of the cylinder surrounding the tubular member.

The means for controlling supply of fluid to the cylinder of the ram will now be described. Referring to Fig. 5, 31 indicates one end of the pipe leading from the pressure chamber 45, Fig. 2, that receives fluid from both pump cylinders, and is in communication with the compressed air containing dome 45. Referring again to Fig. 5, 46 indicates a plug valve mounted in the casing 47. The valve has a supply passage 48 and a discharge pamage 49. When the passage 48 is open the passage 49 is closed. The valve is mounted on a spindle 50 that is moved to and fro by a handle 51. To admit high pressure fluid to the cylinder the handle is moved in a clockwise direction, and to permit the fluid to exhaust from the cylinder it is moved in an anti-clockwise direction. Mounted on the spindle 50 is an arm 52, Fig. 4, which in turn is pivotally united to an arm 53 that is rigidly attached to a rock shaft 54. On the lower end-of the rock shaft is an arm 55 that is pivotally connected to the actuator 40 of the combined check and exhaust valve 39 as described more particularly in connection with Figs. 2 and 3. When it is desired to exhaust fluid from the cylinder to lower the ram the supply passage 48 is closed and exhaust passage 49 opened. Fluid then flows through the pipe 32 to the chamber 22 in the base thus permitting the fluid within the tubular member to escape. The fluid from that portion of the cylinder surrounding the tubular member is permitted to escape through ports 37 and. 38 to the groove 38 and thence to the by-pass 38 which includes the pipe 56 that opens into the pipe 36 leading to the supply chamber or reservoir 22. It will thus be seen that two avenues of escape are provided for the fluid, both discharging in multiple to the reservoir.

It is desirable to have the pump operate all the time and when the valve 46 is turned to a position to close the passage 48 it follows that some means must be provided for taking care of the fluid delivered by the pump. To this end I provide a by-pass 57, Fig. 5, which is controlled by a valve 58, the latter normally being held on its seat by a coiled compression spring 59, the tension of which can be adjusted by the screw 60. When the passage 48 is closed fluid from the pump is discharged through the by-pass into the pipe '32 leading to the reservoir. The valve 58 is set for any predetermined presure. To prevent the ram from being accidentally forced out of the cylinder by fluid pressure I attach to the table a rod 61 that moves in a guide 62 which forms a part of the cylinder 9. The lower end of the rod is threaded and mounted thereon is an adjusting nut 63 by means of which the travel of the ram can be limited.

In order that the operator may ascertain the fluid pressure on the system a pressure gage 64 is provided that is mounted in a T that communicates with the pressure pipe 31 as shown in Fig. 4.

It will be readily appreciated from the foregoing that considerable time can be saved on each operation over prior structures where the ram has a substantially uniform rate of movement. As constructed the ram will rise quickly during the first part of its stroke thereby moving the work to approximately its final position, after which the area of the ram exposed to fluid pressure is greatly increased and the final pressure on the work obtained. In lowering the ram two paths are provided for the fluid to escape, one through the tubular member 33 and the other through the by-pass 38 56, thereby causing the ram and work table to move rapidly downward. The net result of my improved construction is that 100 the operator can perform a greater amount of work in less time because the press works more rapidly, both in elevating and lowering. To state the matter in another way, the time consumed in taking up lost motions 105 is reduced to a minimum.

In accordance with the provisions of the patent statutes, I have described the principle of operation of my invention, together with the apparatus which I now consider to 11 represent the best embodiment thereof; but I desire to have it understood that the apparatus shown is only illustrative, and that the invention can be carried out by other means.

What I claim as new and desire to secure by Letters Patent of the United States, is,

In a hydraulic press, the combination of a cylinder, a double area ram, a double area cylinder therefor, conduit means ad- 120 mitting fluid under pressure to the smaller cylinder area and subsequently to the portion of greater area, controlling valve means for admitting fluid to said conduit means and permitting it to exhaust therefrom, a 125 valve in the cylinder adjacent one end thereof, which opens to permit fluid to enter the cylinder under the suction effect of the larger portion of the ram and closes when the cylinder part of larger area is subjected I to fluid under pressure, and means for positively moving the valve to exhaust fluid from the cylinder.

2. In a hydraulic press, the combination of a cylinder, a double area ram, a double area cylinder therefor, conduit means admitting fluid under pressure to the smaller cylinder area and subsequently to the portion of greater area, controlling valve means for admitting fluid to said conduit means and permitting it to exhaust therefrom, a pivoted slide valve which opens on its pivot to permit fluid to enter the cylinder under the suction eflect of the larger portion of the ram and closes when the cylinder part of larger area is subjected to fluid under pressure, means for positively sliding the valve to exhaust fluid from under the ram, and means for simultaneously moving said controlling valve means and the last named valve.

3. In a hydraulic press, the combination of a ram having a recess, a cylinder therefor, a tubular member carried by the cylinder and arranged in telescopic relation with the recess, said ram controlling the passage of fluid from the member to the outer part of the cylinder, a conduit admitting fluid 1m der pressure to the member, a check valve in the cylinder that opens automatically to permit fluid to enter the main part of the cylinder under the suction eflect of the larger part of the ram and closes when subjected to fluid pressure from said member, a valve means for shutting off the supply of fluid to the member and permitting the fluid to exhaust therefrom, and means for moving the check valve to permit fluid to escape from the cylinder.

4. In a hydraulic press, the combination of a ram having a recess, a cylinder therefor, a tubular member carried by the cylinder and arranged in telescopic relation with the recess, said ram controlling the passage of fluid from the member to the outer part of the cylinder, a conduit admitting fluid under pressure to the member, a hinged check valve in the cylinder that opens to permit fluid to enter the cylinder due to the suction of the ram and closes automatically when fluid under pressure enters the cylinder, supply and exhaust valves for regulating the passage of fluid to the tubular member, and means for moving the check valve with respect to its seat to permit the escape of fluid from the cylinder.

5. In a hydraulic press, the Combination of a base, a fluid containing chamber, a double area cylinder mounted on the base, a double area ram in the cylinder, a pump mounted on the base which delivers fluid at substantially constant pressure and receives fluid from the chamber, a motor also mounted on the base to drive the pump, a valve interposed between the pump and cylinder for regulating the supply of fluid to the latter, an automatic by-pass relief valve actuated by the pressure in the fluid supply that communicates with the high pressure side of the valve and discharges into the chamber, a valve in the cylinder which admits fluid to the cylinder from the chamber due to the suction effect of the portion of the ram of larger area, and means for positively moving the valve to permit the cylinder to discharge into the chamber.

6. In a hydraulic press. the comb nation of a cylinder, a ram located in the cylinder, means for first subjecting a limited area of the plunger to fluid pressure to move it quickly for a portion of its stroke and then a greater area to cause the same to move more slowly and to exert a greater i'orce, a valve in the cylinder that opens under the suction action of the larger area of the plunger to permit fluid to enter the cylinder and closes automatically when fluid under pressure is delivered to the entire cylinder. valve means that controls the admission of high pressure fluid to both parts of the cylinder and the exhaust therefrom, a member to which the first named valve is hinged for moving it with respect to its seat, and an actuator that is common to said member and valve means for simultaneously actuating them when it is desired to lower the ram.

7. In a hydraulic press, the coml'iination of a ram having a recess, a cylinder, a member which enters the recess and :livides the cylinder into two parts when the ram is at one end of its stroke, said member containing a fluid passage, a combined exhaust and check valve that surrounds the member and is located in the cylinder, a pump for supplying high pressure fluid to the number to start the ram and to supply fluid to the entire cylinder to give the final pressure, said check valve permitting fluid to freely enter the cylinder so long as the suction effect of that portion of the ram which surrounds the member exists and closes automatically when fluid from the member enters the entire cylinder, a means to control the supply of fluid to and from said member, and means to move said exhaust and check valve from its seat to permit the fluid under the ram to escape.

In witness whereof, I have hereunto set my hand this third day of December, 1915. GEORGE E. STEVENS. 

